What is the nature of Kant's epistemological formalism, as his critics see it? I will argue that there are several versions, but that in all cases the criticism of formalism amounts to the charge that the outcomes of Kant's method are ultimately subjective. Critics of Kant claim that his insistence that the form of experience arises from our minds, finally makes the empirical world of objects dependent on a form of subjectivity. If our minds introduce the form of experience, so the argument goes, then the objects we experience are only objects ‘for us’ and there is no access to a genuinely extra-mental world. In replying to this in later chapters I will argue that Kant's formalism is an attempt to systematically link the subjective and objective conditions of experience. So while Kant's critics are right to link formalism with a turn to the subject, they are telling only one side of the story. The project of the Copernican revolution is exactly that of showing how the turn to the subject will secure the possibility of knowledge of an objective world. But the full version of this project does not involve reducing objectivity to the subjective conditions of experience, which are necessary and not sufficient. Later I take up the problem of the empirical applicability of the subjective forms of thought by emphasising the aesthetic dimension of Kant's critical turn.